<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 1,0,0 */
        #one-id {
            color: blue;
        }

        /* 0,1,0 */
        .one-class {
            color: red !important;
            font-style: italic;
        }
        
        /* 0,0,1 */
        div { 
            color: green;
        }
    </style>
</head>

<body>
    <div class="one-class" id="one-id">class选择器条目1</div>
</body>

</html>